Increased attention to ergonomics in sedentary office settings has led to the design of chairs that require “active” sitting. These chairs (“active chairs”) encourage different kinds of movement, including forward and backward movement, side to side movement, rotation, and wobbling through a 360° range of rotation around a vertical axis. An example of one configuration is shown in U.S. Pat. No. 7,547,067, incorporated by reference. Another example of an active chair is the “ErgoStool” offered by Autonomous Smart Office. The benefits of active sitting and active chairs are well recognized. Most active chairs return to a substantially vertical position when they are not in use.
But there is a significant shortcoming of active chairs that has not been previously recognized—a user may get in the habit of slightly leaning in one direction, with the chair realigned to accommodate this lean by tilting in the opposite direction. The amount of lean and tilt is minor, and would often not be noticed by the user (whose body has subconsciously compensated for the tilt in order to feel balanced). In fact, most users using an active chair would be pleased with the perceived benefits of the chair and would expect that they were sitting straight and improving their posture. An observer would often not notice the lean or resulting body alignment compensation either. But over time this leaning may lead to posture issues, as shown in FIG. 6. In addition, if the active chair is not positioned directly in front of the work surface, a user may not shift the location of the chair and instead try to align themselves with the work surface by leaning to one side or the other, again with negative posture implications.